Variable frequency counter



July 22, 1952 o, acsoRLEY 2,604,263

VARIABLE FREQUENCY COUNTER Filed May 22, 1947 2 SHEETSSHEET l 3nveutorQwLMg/may g 082M Q avg; (Incl-neg Patented July 22, 1952 VARIABLEFREQUENCY COUNTER "01in MacSorley, Collingswood, N. .L, assignor toRadio Corporation of America, a corporation of Delaware Application May22, 1947, Serial No. 749,849

10 Claims.

This invention relates to variable frequency counters such as areadapted (l) to provide a wide range of variation between the frequenciesof their input and output pulses and (2) to automatically reset to theirzero count or standby condition when the counting cycle to which theyare adjusted is completed. Such devices include control means which areadjustable either to maintain a constant output frequency in response toa variable input frequency or to provide a variable output frequency inresponse to a constant input frequency. The present invention isillustrated as adapted to provide a constant output frequency inresponse to an input frequency which is adjusted in steps.

A variable frequency counter adapted to provide a variable outputfrequency in response to a constant input frequency is disclosed in acopending application'of W. H. Bliss, Serial No. 736,214, filed March21, 1947, now Patent No. 2,521,774, issued Septemberl2, 1950. Thecounter of this copending application is disclosed as including fourdecades. Control of each of these decades to select any desired count iseffected by means of a switch having three movable contacts which aremechanically fixed together, are connected to a common terminal, andengage separate rows of fixed switch contacts as they are moved from oneposition to another. These fixed contacts are connected to the anodes ofthe decade and are so arranged that counts of to 9 are selected as themovable contacts of the switch are moved from their firstto their tenthoperating position. Each time the count of a decade corresponds to thatfor which the switch .is set, a more positive pulse is applied to thecommon terminal of the three contacts. When the overall countcorresponds to the switch setting of all the decades, a control circuitis energized to deliver a pulse which is applied to an output terminaland is also utilized to automatically reset the counter to its zerocount condition.

The variable frequency counter of the present invention is similar tothat of the aforesaid application in that it includes a series ofdecades which are connected in tandem and each include a three-pointswitch for selecting any desired .count of the decade. It isdistinguished from the invention of the aforesaid application in thatimproved means are provided for automatically re- .setting the counterto its zero count condition, provisions are made for accelerating theaction of the high speed decade to which the input pulses are applied,and one of the decade selector switches is combined with that of a twostage counter to produce a desired result.

The principal object of the invention is to provide an improved variablefrequency counter and method whereby a constant frequency output may bederived in response to a variable frequency input. Important objects ofthe invention are the provision of improved means for resetting avariable frequency counter; the provision of means for ensuring reliableoperation of a counter at high operating frequencies; and the provisionof means for combining the count selection switches of the low speed orhigh order end of the counter. a

The invention will be better understood from the following descriptionconsidered in connection with the accompanying drawings and its scope isindicated by the appended claims.

Referring to the drawings:

Fig. 1 is a wiring diagram of a variable frequency counter connected inaccordance with the invention;

Figs. 2 to 5 are explanatory curves relating to the operation of thecounter of Fig. 1; and

Fig. 6 is a wiring diagram of a modified trigger circuit which may beused in the high speed decade of the variable frequency counter of Fig.1.

The counter of Fig. 1 includes a high speed decade comprising theduotriodes 20 to 23, an intermediate speed decade comprising theduotriodes 24 to 21, a low speed decade comprising the duotriodes 28 to3| and two additional duotriodes 32 and 33. Input pulses 295 of negativepolarity are applied from a lead 34 through the crystal diodes 35 and 36to the grids of the duotriode 20. Output pulses are applied from anoutput lead 31 through a capacitor 38 to a reset circuit which includesa duotriode 39 and a tetrode 4D. The number of input pulses required toproduce one output pulse is determined by the setting of the selectorswitches of the different decades. If the output frequency is to bemaintained constant, it is necessary that the setting of the selectorswitches be changed at each change in input frequency.

These selector switches 81, 94, and 96, which are shown immediatelybelow the decades which they control, have their movable contactsconnected through gates of the duotriode type to the output terminal 31.Thus the three movable contacts 4|, 42 and 43 of the selector switch ofthe decade 20-23 are connected through the duotriodes 44, 4'5 and 46 andthe leads 4! and 48 to the output lead 3'! so that the lead 3'! is mademore positive when the count of the decade 2ll-23 corresponds to thesetting of the movable contacts 4I--42-43 of the selector switch of thisdecade. Likewise the three movable contacts 49,

50 and 5| are connected through a duotriode 52 and a lead 53 to theoutput lead 3'! so that this lead is made more positive when the countof the decade 24-21 corresponds to the setting of the contacts 49, 50and 5|. Similarly, the three movable contacts 54, 55 and 56 of theselector switch of the decade 28-3l and the single movable contact 5'!of the selector switch of the counter units 32 and 33 are connectedthrough a duotriode 58, a lead 59 and the lead 48 to the output lead 31so that this lead is made more positive when the count corresponds tothe setting of the contacts 54 to 51. I

During the counting operation, the more positive potentials mentionedabove must be simultaneously applied to the output lead 3'! in order toactivate the reset circuit. Thus a more positive potential isestablished at the lead 59 when the count of decade 28-3l and stages 32and 33 corresponds to the setting of the contacts 54 to 52', at the lead53 each time the count of decade 24-21 corresponds to the setting ofcontacts ii), 50 and 53, and at the lead 41 each time the count of thedecade -23 corresponds to the setting of the contacts 41,42 and 43. Whenthese three potentials are -all at their most positive value, the resettube 39 is biased on and one output pulse is produced at a lead '69which is connected to a counter reset lead 61 and the output lead 62.

The character of the pulses produced at the leads 3'! and 60 are to bediscussed hereinafter in considerable detail for the reason that theyrelate to important features of the invention. As already indicated,these pulses are dependent on the potentials produced at the fixedterminals of the various selector switches by the trigger circuits ofwhich the counter is constructed. It "is therefore necessary to considerthe circuit connections of the trigger circuits, their interconnectionswith one another, their connections to the fixed contacts ofthe'selector switches, and the arrangement of these fixed contacts withrespect to one another. v

All the trigger circuits of the counter are of a type wherein twotriodes each has its anode crossresistor shunted by a capacitor so thatcurrent conduction is in either one or the other of the triodes. s 7 sThus the first trigger circuit of the decade 28-23 has its anode 6'5cross-connected to its grid 68 and its anode 66 cross-connected to itsgrid 61.

The cathode of this trigger circuit is grounded through resistors 63 and64 and operating potential is applied to the anodes 65 and 66 from a +3lead 69 through a resistor Hi which functions to maintain all the anodesof the decade at the potential level required for proper operation ofthe counter. With these connections, the application of a negative pulsefrom the lead 34 through the diode crystals and 36 to the grids 61 and68 functions in a well known manner to transfer current conduction fromthe conducting to the non-conducting triode of the trigger circuit.

The other three trigger circuits of the decade 20-23 are similar to thefirst. All of them are connected in tandem through the couplingcapacitors l3, l4 and 15. An important feature of the decade 20-23 isthe connection of the anode 16 of the last stage through a crystal diode11 to the right-hand grid 18 of the third stage and through a diodecrystal 19 to the right-hand grid 80 of the second stage. With theseconnections, the operation of the decade 20-23 is as indicated by thefollowing tabulation wherein the number connected to the grid of theother through a of pulses applied to the input lead 34 are shown in thefirst column and the current conductin condition of the various stagesare indicated by R (righthand triode) and L (left-hand triode).

Tabulation No. 1

Trigger Circuit Number Pulse No.

R R R R L R R R R L R R L L R R R R L R L R L R R L L R L L L R R R R LL L L L L L L R R R R It is apparent from the above tabulation that anegative pulse is produced at the anode '15 of the last stage in'responseto eight input pulses and at the anode 81 of this stage inresponse to ten input pulses.

Such negative pulse at the anode '16 functions to transfer currentconduction from the righthand triodes to the left-hand triodes ofthe-second and third stages so that the operating cycle of the decade29-23 is completed in response to ten input pulses. This type offeedback is disclosed in a copending application of I.'E.'Grosdofi, Ser.No. 580,446, filed March -1, 1945, now Patent No. 2,521,788, issuedSeptember 12, 1950.

Output pulses of negative polarity are fed to the input terminal 82 ofthe decade 24-21 through a capacitor 83 from oneor the other of theanodes i8 and 8| depending on the setting of themOvable contact 83 whichcooperates with fixed contacts 0, I, 2 and 3 (connected to the anode 16)and fixed contacts 4 to 9 (connected to the anode 8|). This switch as awhole is indicated by the reference numeral 84. Its purpose ishereinafter explained in connection with the form'of pulse which iseffective to operate the reset circuit previously mentioned. I

Associated with the decade 20-23 is a switch which includes amoVablecontact-BB and fixed contacts 0 to 5. The function ofthisswitch-is to connect the right-hand grid 68 of the first stage to thereset lead 61 only when this stage is not in its zero count condition.The purpose of this is to avoid interference between the'inp'u't pulseswhich may be applied continuously and the reset pulse which might"otherwise operate the stage to produce inaccuracy of the count.

The three point switch which controls the application of the anodepotentials of the decade 20-23 to the gates 44, 45 and 46 *is indicatedby a general reference numeral '8'! for convenience of reference. itincludes the'mova'bl'e contacts 4|, 42 and 43 and'th'ree correspondinggroups of fixed contacts. Each group of fixed contacts is numbered 0 to9 like the fixed contacts of the switches 84 and 85. As indicatedby'b'r'oke'n lines, the movable contacts of the's'witches 84, 85 and 81may be all'gangecl "togethe'rso that each" movable contact engages the"same "numbered fixed contact in all the switch positions.

By' assuming any desired position or the movable contacts 4|, 42 and 4-3of the switch fljl are all least positive only when the'numbe'r 'ofinput pulses corresponds to thepa'rticula'r switch setting. Thusif theswitch 81 is set at the number 5 contacts which are connectedrespectively to the left anode of the first stage, the right anode ofthe second stage and the left anode of the third stage, it is evidentfrom the tabulation that the movable contacts 4|, 42 and 43 are all attheir more negative potentials only when five input pulses have beenapplied to the lead 34. The same is true for all the other settings ofthe switch 81.

As hereinafter explained in greater detail, these more negative pulsesof the movable contacts 4|, 42 and 43 are combined and reversed by thetriodes 44 and 45, then passed through the gate 46 to give a singlereversed pulse which is again reversed and amplified by the second halfof the duotriode 46 so that a more positive pulse is applied to the lead41.

The remaining stages of the counter differ from the stages of the decade20-23 in that (l) anode potential is applied from the lead 69 through acommon resistor 83 to the individual anode resistors, (2) input pulsesare applied between the different stages through capacitors 89 to aterminal at the junction of the common and individual resistors, (3)feedback connections of the decades 24-21 and 28-3l are made throughcapacitors 90 to 93 instead of crystal diodes, and (4) the feedback ineach decade is from the last to the third and from the third to thesecond instead of from the last to the second and third stages.

The use of crystal diodes in the grid circuits of the first decade 20 to23 has the advantage that it facilitates more rapid operation of thisstage. The second and third decades operate at speeds which permit theuse of capacitors throughout the circuit. It is, of course, apparentthat the decade 24-21 counts tens, the decade 23-3! counts hundreds, andthe stages 32 and 33 count thousands. The operation of the decade 24-21is apparent from the following tabulation wherein the input pulses areeach indicated as a group of 10.

Tabulation No. 2

The operation of the decade 28-3! is similar to that of the decade 24-21with the exception that each impulse applied to it represents 100 pulsesapplied to the lead 34. Similarly, each input pulse to the stages 32 and33 represents 1000 input pulses applied to the lead 34.

Three oint switches 94 and 95 similar to the three point switch 81 areprovided for applying the anode potentials of the decade 24-2! and thedecade 28-3l respectively to the gate 52 and the gate 58. Ganged withthe switch 95, as indicated by a broken line, is a switch 96 by whichthe counts of the stages 32 and 33 are combined with the counts of thedecade 28-3] to produce a result to be explained in greater detail.

Assuming the switch 94 to be set fora count of 70, as indicated by thenumeral '7 adjacent its corresponding fixed contact, it is seen that themovable contact 49 is connected to the righthand anode of the stage 24,the movable contact 50 is connected to the left-hand anode of the stage25, and the movable contact 5| is connected to the right-hand anode ofthe stage 21. Referring to Tabulation No. 2, it is seen that all theanodes to which these movable contacts are connected are not conductingcurrent in response to the 70th input pulse and are therefore at theirmore positive potentials. These more positive potentials are combinedand amplified in the gate 52 and function to produce a more positivepulse at the lead 53. In the same manner, each setting of the switchresults in a more positive potential at the lead 53 when the number ofinput pulses correspond to the selected setting of the switch 94.

While the decade 28-3] is similar to the decade 24-21, its three pointswitch has a somewhat different arrangement .of its fixed contacts asindicated by the reference numerals which are adjacent the fixedcontacts and have the same significance'as in the cases of the switches81 and 94.

Assuming the switches 95 and 96 to be set in their illustratedpositions, it will be noted that the contact 54 is connected to theleft-hand anode of the stage 28, the contact 55 is connected to theright-hand anode of the stage 30, and the contact 51 is connected to theleft-hand anode of the stage 3|. Since all these anodes are notconducting current at a count of four hundred input pulses and aretherefore at their more positive potentials, a more positive potentialtends to be applied to the gate 58. This potential is not sufficient toopenthe gate because of the negative potential applied to it from therighthand anode of the stage 32. When the number of input pulses reaches1400, however, the gate 58 is opened and the lead 59 is made morepositive.

As the movable contacts 54, 55, 56 and 51 are moved to the right, thegate 58 is opened successively in response to input pulses numbering1500, 1600, 1700, 1800, 1900, 2000, 2100,2200 and 2300. Thisparticular-arrangement is provided to facilitate the maintenance of aconstant frequency of 31.25 cycles at the output terminal 62 while theinput frequency at the lead 34 is changed by equal steps from 43,750 to74,6875 cycles.

- With the switch settings previously assumed, one output pulse isproduced in response to 1475 input pulses. Such a single output pulsemay be produced by input pulses numbered from 1400 to 2399 with theswitches 95 and 96 ganged together as illustrated. 'Thus if the inputfrequency is 43,750 cycles and the output frequency is to be kept at31.25 cycles, the selector switches are set at 1400. Similarly theselector switches are set at 1410 for an input frequency of cycles at1430 for an input frequency of 16 cycles at 1440 for an input frequencyoi.

cycles cycles, etc.

As indicated above but'not explained in detail, the anode voltages ofthe various stages of the counter are applied through the three pointselector switches 81, 94 and 95 and the one point switch 96 to theisolating-tubes 44 and 45 and to. the gate tubes 40, 52 and-58 forproducing a reset or output pulse in response to a number of inputpulses corresponding to the setting of the selector switches.

These tubes are illustrated as of the duotriode type, only one of thetriodes being utilized in the case of 44. The more negative potentialsof the switch 81 are applied respectively to the grid of the tube 44 andto the grids of the tube 45. As a result, the tubes 44 and 45 draw lesscurrent through their anoderesistors and a more positive potential isapplied to the left-hand grid of the gate 46. When all three of thetriodes of '44 and 45 are non-conducting, sufficient voltage is appliedto the grid to override the (bias and cause 46 to conduct, thusincreasing the current of its left-hand triode and applying a morenegative potential to its right-hand grid so that the current of itsright-hand triode is reduced and a more positive potential is applied tothe lead 41.

In previously known means of combining the anode voltages of a decadecounter, it has been customary to insert large isolating resistors inthe fixed contact leads of the selector switch and to connect theselected ones of these resistors through the movable switch contacts toa common terminal which is connected to the grid of the gate tube. Thedisadvantage of such a combining system is that the large isolatingresistors in series with the input capacity of the gate tube produces aslope on the leading edge of the pulse applied to the grid of the gatetube so that the gate tube is operated a fraction of a cycle late.

By using the threeisolating triodes 44 and 45, as explained above, thegate tube control voltage wave is made to have about the same steepnessas those ofthe anode voltage waves. At the same time there is maintainedsuch complete isolation between the anodes of the decade as is requiredto prevent interference with the operation of the decade by variation inthe selector switch settings.

It should 'be noted that the cathodes of the isolating tubes 44 and 45are all connected together and are so biased as to conduct only when amore positive voltage is applied from the selected anodes of the decade.

The operation of the gate tubes 52 and '58 is readily understood withoutdetailed explanation. When a more positive pulse is applied from theselected anodes to their left-hand grids, more current is drawn by theirleft-hand triodes, the potentials of their right-hand grids is made morenegative, the current of their right-hand triodes is reduced and morepositive potentials are applied to the leads 53 and 59.

The more positive potential which is applied to the lead 31 in responseto the selected number of pulses applied to the input lead 34 is now tobe considered in connection with Figs. 2 to 5. Fig. 2 is a diagrammaticindication of the composition of the potential applied to the lead 31.The potentials applied through gate 48 are indicated by straight lines,the potentials applied through the gate 52 are represented by squarewaves of short width, and the potentials applied through the gate 58 areindicated as square waves of larger width.

It will be noted that these gated potentials are superimposed on oneanother, as indicated by the reference numeral 91, when the number ofpulses applied to the input lead 34 corresponds to the setting of theselector switches 81, 94, and 95. This pulse 91 makes the right-handgrid of the peak detector 39 more positive, more current is drawnthrough the right-hand anode resistor, the potential of the left-handgrid is made more negative, less current is drawn through the lefthandanode resistor and a positive pulse potential is applied to the grid ofthe tube 40. As a result, the tube Mitriggers, drawing a large pulse ofcurrent through its cathode resistor and a positive pulse potential isapplied to the lead 60. This potential is applied (1) to the output lead'62 and (2) to the reset lead 6| which is connected to the right-handgrids of the various stages of the counter. When this more positivepotential is so applied to these right-hand grids, all the stages of thecounter are reset to their zero count or standby condition with currentin their right-hand anodes. The effect of this on the potentials at 3!is shown in Fig. 2.

In connection with Fig. 2, it has been assumed that all the voltageschange instantaneously. Actually, the step fromthe potential of thesecond gate to that of the first gate may have a curvature on its frontedge as indicated at 98 in Figs. 4 and 5 wherein the anode potentials ofthe first and second decade are shown much wider than in Fig. 1.Assuming the pulses of the first gate to have straight sides, thiscurvature results in a control and reset pulse occurring a fraction of asecond later than it should.

Such inaccuracy is minimized or obviated by the provision of the switch84 connected between the first and second decade. This switch functionsto advance the time (but not the rate) at which pulses are fed to thesecond decade when its movable contact 83 is in engagement with thefixed contacts 0 to 3. The resulting effect, as indicatedby Fig. 5, isto advance the beginning of the Second Gate potential so that the First.Gate potential is not superimposed on the curved portion 98 of theSecond Gate potential. In this manner, correct timing of the reset andoutput pulses is assured. This feature is, of course, useful in manyother cases where superimposed voltages are derived through a pluralityof gates from sources of potential which are of a wave form subject tocurvature.

In resetting a variable frequency counter, such as that of the presentinvention, the most critical point is the first stage of the highfrequency decade. The first stage must trigger rapidly and be ready toaccept the next input pulse with a minimum of delay- Before the countercan begin anew count it obviously must be reset to' its initialcondition. If the first stage of the counter has been left by theprevious count in its zero count condition, with current in its righthand anode, a condition which occurs for even counts, the first stageneed not be reset. It is advisable not to apply a reset pulse to thestage-when in its zero count condition, since this may cause holdover,and the next applied pulse to be counted may be missed. If, as theresult of an odd-numbered count, the first stage is left in a conditionwith current in its left hand anode, it must be reset to its zero countcondition in order to function properly for the new count. For all oddnumbered settings of the selector switch which derive a voltage from theleft anode, this first stage must be reset and ready to operate in lessthan one cycle so that no counts are missed. For all even numberedsettings of the selector switch which derive a voltage from the rightanode, the first stage must not be reset and must not hold over for anextra cycle. These conflicting requirements are met by applying thereset potential to the right-hand grid of the first stage of the highfrequency decade only on the odd counts. This is accomplished by theswitch 85 which has its odd numbered fixed contacts connected to thereset lead GI and has its movable contact 86 connected through arelatively high resistance to the right hand grid of the first stage sothat the reset pulse applied to this grid is of an amplitude reduced tothe optimum value for the condition under which this stage is operated.The first stage is thus reset at a maximum speed.

The feed-back connections of the decades 20-23, 24-21 and 28-3! may bemodified as indicated by Fig. 6. This modification consists in feedingback from the left-hand anodes of the stages 21 and 26 to right handgrid of the stage 25. The operation of the decade with this type offeedback is shown by the following tabulation which has the samesignificance as the previous tabulations.

Tabulation No. 3

Trigger Circuit Number Input Pulse No.

R R R R R R L R R L R R R L R L .r L L R R R L L L R L R L L L L L L R RR With this type of feedback, it is essential that the feedback couplingunits 99 and be unilateral conductors so that the feedback pulses are ofonly one polarity; otherwise the feedback pulse from stage 21 would becancelled by one of opposite polarity from stage 26. The advantage ofthis type of feedback connection is that it produces in the variousstages wave forms more suitable for use for some applications than thoseproduced by the feedback connections shown by Fig. 1. How the fixedcontacts of the selector switch are to be connected to the anodes ofthis decade is apparent from the above Tabulation No. 3.

What the invention provides is (1) an improved counter which is operableto produce a constant frequency in response to a variable frequency orvice versa, (2) an improved circuit connection for resetting the firststage of the high speed decade of the counter, (3) an improved system ofcombining the potentials selected from different groups of counterstages to produce an output-pulse which is accurately shaped, (4) animproved means of channeling the selected'anflde potentials of a decadeto the gate through which they are passed for combination with similarpotentials from other decades or groups of stages, (5) means for interconnecting a higher speed decade or group of stages with a lower speedgroup of stages so that one selected count of the lower speed group iscombined with one selected part of the counts of the high speed groupand another selected count of the low speed group is combined withanother selected part of the counts of the high speed group, and (6) adecade counter with an improved system of feed-back connections wherebyvoltage disturbances in the various stages of the decade are minimized.

I claim as my invention:

1. The combination of a counter having a plurality of tandem-connectedstages each including a pair of electron discharge elements which haveoperating potential applied to their anodes through separate impedanceelements and have their grids each connected to the anode of the othersothat current conduction is stable either in one or the other of saidelements, means for applying a reset potential to a corresponding gridof all but the first of said stages, and'means for applying to thecorresponding grid of said first stage a reset potential of a value,different from that applied to the corresponding grids of the other ofsaid stages.

2. The combination of acounter having a plurality of tandem-connectedstages each including a pair of triode elements which, have operatingpotential applied totheir anodesthrough separate impedance elements andhave their grids each connected to the anode of the other so thatcurrent conduction is stable either in one or the other of saidelements, a source of reset potential, a plurality of resistanceelements having substantially the same value each connected between saidsource ,of reset potential and a corresponding grid of all but the firstof said stages, and meansfor connecting a resistance element having avalue which is high relative to the value of one of said plurality ofresistance elements be tween said source and the corresponding grid ofthe first of said stages.

3. The combination of acounter having a plurality of tandem-connectedstages each including a pair of electron discharge elements which. haveoperating potential applied to their anodes through separate impedanceelements and have their grids each connected to the anode of the otherso that-current conduction is stable either in oneor the other of saidelements, a source of reset potential, a plurality of resistanceelements each connected between said source of reset potential and acorresponding grid of all but the first Of said stages,,and means forconnecting a resistance element having avalue which is high relative tothe value of one ofsaid plurality of resistance elements and a capacitorbetween said source and the corresponding grid of the first of saidstages.

4. The combination of a counter having a plurality of tandem-connectedstages each including a pair of triode elements which have operatingpotential applied to their anodes through separate impedance elementsand have their grids each connected to the anode of the other so thatcurrent conduction is stable either in one or the other of saidelements, means for applying a reset potential to a corresponding gridof all but the first'of said stages, and means for applying a resetpotential to the corresponding grid of said first stage only when saidfirst stage is not in its zero count condition. I

5. The combination of a counter having a plurality of tandem-connectedstages each including a pair of electron discharge elements which haveoperating potential applied to their anodes through separate impedanceelements and have their grids each connected to the anode of the otherso that current conduction is stable either in one or the other of saidelements, means for applying a reset potential to a grid of all but thefirst of said stages, means for applying a reset potential to a grid ofsaid first stage only when said first stage is not in its zero countposition, means connected to said anodes for selecting groups ofpotentials which are made of one polarity simultaneously in response tothe application of successive pulses to the first of said stages, meansincluding a plurality of triode elements having their grids connected tosaid se lecting means for producing a single potential responsive tosaid selected potentials, and means including a pair of triode elementsresponsive to said single potential for producing a potential which isrepresentative of the selected count of said counter.

6. The combination of a counter having four stages each including a pairof triode elements which have operating potential applied to theiranodes through separate impedance means and have their grids eachconnected to the anode of the other so that current conduction is stableeither in one or the other of said elements, means for interconnectingsaid stages so that the operating cycle of said counter is completed inresponse to the application of ten pulses to the first of said stages,means for applying a reset otential to a grid of all but the first ofsaid stages, means for applying to the corresponding grid of said firststage a reset potential only when said first stage is not in its zerocount position, means to attenuate said reset potential applied to saidfirst stage to have its optimum reset value, means connected to saidanodes for selecting groups of three potentials which are made of onepolarity in response to the application of successive pulses to thefirst of said stages, and means connected to said potential groupsselecting means to produce a single potential in response to saidselected potentials.

7. The combination of a counter having different groups of stages eachof which stages includes a pair of electron discharge elements havingoperating potential applied to their anodes through separate impedancemeans and having their grids each connected to the anode of the other sothat current conduction is stable either in one or the other of saidelements, means interconnecting the stages of each group so that itsoperating cycle is completed in response to the application of apredetermined number of input pulses, said different groups beingconnected in tandem, switch means to connect a first of said groups to asecond of said groups to advance the time of application of drivingpulses from said first group to said second group for low orders ofcounts in said second group, separate means connected to the anodes ofeach group for selecting potentials which are made of the same polarityin response to successive ones of its input pulses, and means forcombining all of said selected potentials to produce a single potentialrepresentative of said selected potentials.

8. The combination of a counter having different groups of stages eachof which stages includes a pair of triode elements having operatingpotential applied to their anodes through separate im- 12 pedance meansand having their grids each connected to the anode of the other so thatcurrent conduction is stable either in one or the other of saidelements, means interconnecting the stages of each group so that itsoperating cycle is com pleted in response to the application of apredetermined number of input pulses, said difierent groups beingconnected in tandem, switch means to connect the last stage of a firstof said groups to the first stage f a second of said groups to advancethe time of application of driving pulses from said last stage to saidfirst stage for low orders of counts in said second group, separatemeans connected to the anodes of each group for selecting potentialswhich are made of the'same polarity in response to successive ones ofits input pulses, and means for combining all of said selectedpotentials to produce a single potential representative of said selectedpotentials and means responsive to the peak of said single potential forproducing an output pulse.

9. The combination of a counter having dinerent groups of stages each ofwhich stages includes a pair of electron discharge elements havingoperating potential applied to their anodes through separate impedancemeans and having their grids each connected to the anode of the other sothat current conduction is stable either in one or the other of saidelements, means interconnecting the stages of each group so that itsoperating cycle is completed in response to the application of apredetermined number of input pulses, said groups being connected intandem, a selector switch connecting one of the anodes of the last stageof a first of said groups to the first stage of a secondof said groupsto advance the time of application of driving pulses from said laststage to said first stage for low orders'of counts in said second groupand connecting the other of the anodes of said last stage to said firststage for high orders of counts in said second group, separate meansconnected to the anodes of each group for selecting potentials which aremade of the same polarity in response to successive ones of its inputpulses, and means for combining all of said selected potentials toproduce a single potential representative of said selected potentialsand means responsive to the peak of said single potential for resettingsaid counter to its zero count condition.

10. The combination of a counter having difierent groups of stages eachof which stages includes a pair of triode elements having operatingpotential applied to their anodes through separate impedance means andhaving their grids each connected to the anode of the other so thatcurrent conduction is stable either in one or the other of saidelements, means interconnecting the stages of each group so that itsoperating cycle is completed in response to the application of apredetermined number of input pulses, said groups being connected intandem, a selector switch con necting one of the anodes oi. the laststage of a first of said groups to the first stage of a second of saidgroups to advance the time of application of driving pulses from saidlast stage to said first stage for low orders of counts in said secondgroup and connecting the other of the anodes of said last stage to saidfirst stage for high orders of counts in said second group, separatemeans connected to the anodes of each group for selecting potentialswhich are made of the same polarity in response to successive ones ofits input pulses, said switch means being connected to said first groupselecting means to be adjustable therewith, means for combining all ofsaid selected po- 13 s 14 tentials to produce a single potentialrepresenta- Number Name Date tive of said selected potentials, meansincluding a 2,407,320 Miller Sept. 10, 1946 triode element so biased asto conduct current 2,411,714 De Rosa Nov. 26, 1946 only in response tothe peak of said combined 2,416,095 Gulden Feb. 18, 1947 singlepotential, and means responsive to said 5 2,422,698 Miller June 24, 1947peak-produced current for producing an output FOREIGN PATENTS pulse.

N L, L Y, Number Country Date 355,705 Great Britain Aug. 24, 1931 Thefollowing references are of record in the vacuum Tube scaling Circuitsof Arbi me of this patent: trary Integral or Fractional Scaling Ratio;Lif- UNITED STATES PATENTS schultz Phys. Review, volume 57; p. 243,1940.

Number Name Date 15 2,381,920 Miller Aug. 14, 1945

